Exploration of a geothermal system fully constructed from composite materials

Geothermal energy can substantially contribute to lower CO2 emissions for heating of greenhouses and buildings. Geothermal production typically can be divided in High Temperature (HT) and Low Temperature systems (LT). HT can serve as source for electricity production and LT (typically below 100 °C, or 212 °F) for local direct heating. The...

Optimization and redesign of a structurally loaded fused filament fabrication component: Numerical and experimental validation - Preprint -

Additive manufacturing provides the possibility to manufacture parts on demand and offers tremendous form freedom compared to traditional manufacturing methods. However, Fused Filament Fabrication (FFF) is not yet widely used for highly structurally loaded parts, as their strength is hard to control and to predict. In this work we aim to analyze...

Assessment of the technical safe limit speed of a non-ice-strengthened naval vessel with representative and alternative side shell designs in ice-infested waters

Sailing in ice-infested waters has become more relevant for the Royal Netherlands Navy (RNLN). A method is developed to determine the technical safe speed for a single ice floe impact with a typical non-ice strengthened naval vessel. A representative ice floe impact load scenario is applied to three structural arrangements for the side shell...

A new analytical approach for describing fatigue load sequence effects

Load sequence effects in fatigue crack growth, such as retardation and acceleration due to a large overload (OL) and underload (UL), can dramatically change the (remaining) fatigue life. These effects can be determined using analytical and numerical tools, often trading accuracy for a steep increase in required calculation time. This paper...

The thickness effect in adhesively bonded joints: An experimental study

It is known that bond line thickness has an effect on the strength of adhesively bonded joints. However, most of the work done in this area focussed on bond lines up to 3 mm thick. In this paper the thickness effect is studied of bond lines up to 10 mm thick, which is a typical thickness for civil infrastructure and maritime applications. An...

A new model for fatigue load sequence effects in offshore wind turibne substructures and its implications for design life

Measurements at Offshore Wind Turbine (OWT) substructures show that typical loading patterns include overloads, underloads, and shifts in mean stress cycles, due to the everchanging wind direction. These events follow each other in time and are further expressed as load sequences. Load sequences may affect the fatigue life. A novel model...

Approach to include load sequence effects in the design of an offshore wind turbine substructure

Fatigue is one of the main design drivers for offshore wind substructures. Using Fracture Mechanics methods, load sequence effects such as crack growth retardation due to large load peaks can be included in the fatigue damage estimation. Due to the sequence dependency, a method is required that represents the sequences of loads in the design or...

New tools for asset management of offshore wind support structures

design driver for Offshore Wind Turbine (OWT) substructures and also has an im-pact on operational costs. During service life, inspections are required to detect fa-tigue cracks at an early stage. These cracks may need to be repaired. The costs of in-spections and repair are high for offshore structures. To reduce the cost of energy, it is...

Innovative fatigue prediction model for improved fatigue performance of welded steel connections in offshore wind turbine jackets

Offshore Wind power is considered one of the fastest growing maritime sectors and the most promising sources of ‘clean’ energy towards meeting the European targets for 2020 and 2050. The growth of the sector has also been mirrored in other continents like China and US. The technology keeps rapidly growing and the top offshore turbine makers in...

Including load sequence effects in the fatigue damage estimation of an offshore wind turbine substructure

Retardation is a load sequence effect, which causes a reduced fatigue crack growth rate after an overload is encountered. Retardation can be cancelled when the overload is followed by an underload. The net effect is beneficial to the fatigue lifetime of Offshore Wind Turbines (OWTs). To be able to take this into account, computationally...

An approach to using Weibull stress analysis in design

Current codes and norms allow for structures to be operated in the transition between ductile and brittle behavior. Further, they often treat the Ductile to Brittle Transition Temperature as a constant even though it is well known to depend on a variety of factors, such as loading rate, constraint, and prior cold deformation. This paper roposes...

Testing of full scale composite journal bearings for offshore underwater applications

In the offshore industry, fibre reinforced sliding journal bearings are increasingly used due to their low-maintenance and self-lubricating characteristics. To be able to use the bearings in the rough offshore environment, under heavy loading, full scale tests are essential to assess the friction and wear rate development during use. For this...

Calculation of shell element failure based on the state of stress inside of a neck

Simulation of failure in thin-walled structures is critical for the correct determination of crash performance of ships and offshore structures. Typically, shell elements are used, but these elements are not able to adequately capture local failure, especially inside of a neck. This paper addresses these gaps by adapting the Bridgman (1952)...

Use of current S355 and S690 steels for arctic applications

In this paper, the applicability of currently-available S355 and S690 steels to Arctic applications is estimated according to current classification rules. A database of results used for quality control for offshore structures that were not necessarily designed for Arctic operations was analyzed. The results needed to be extrapolated to lower...